[l2h] netpbm 9.8 & cropping bars

Ross Moore Ross Moore <ross@ics.mq.edu.au>
Fri, 10 Nov 2000 17:55:27 +1100 (EST)

> Bruce R Miller wrote:
> > 
> > Unfortunately, I'm now getting those infamous cropping bars.
> > Has anybody figured out what adjustments to make?   Or any pointers as
> > how to best determine what to adjust?
> I had the same "cropping bar" problem.
> After some investigation I found out that the problem is,
> that 
>  "pnmcrop -bot"
> doesn't works with the new pnmcrop version.
> I think this is because two edges of the image which has to be cropped 
> are black and two are white, so pnmcrop thinks that black is
> the foreground color and doesn't crops the black bars.

The old version would crop a whole edge, provided it was all the same
color. It didn't need to be black or white.
When cropping all around, I think it was the right-hand edge which
was examined to determine the color to be cropped.
> I hacked my pstoimg script so that it works with the new pnmcrop tool,
> but I don't know how compatible my changes are.
> But perhaps this gives Ross the right idea where the problem lies :)
> Here is my hacked, new version:
>   # RRM: Remove justification bars
>   $EXTRA_CROP =~ s/h/bt/gi; # crop horizontally
>   $EXTRA_CROP =~ s/v/rl/gi; # crop vertically
>   while ($EXTRA_CROP =~ /([atblrs])/gi) {
>     my $edge = $1;
>     my $croparg = '';
>     if($edge =~ /b/i) {
>       $croparg = '-black -bot ';

>     } elsif($edge =~ /[tlr]/i) {
>       $croparg = "-black -$edge ";

>     } elsif($edge =~ /s/i) {
>       #RRM: shave at most 1-2 rows of white from the bottom
>       if($cmd) {
>         # Terminate command pipe
>         &do_cmd($in,$tmp,$cmd) || return 0; # failure
>         $cmd = '';
>       }

With the TeX code currently placed into the header of  images.tex  there
is no reason to assume that the cropping-bars will be black.
They are the same as the \current@color  used for ordinary text.

Your suggested edit will thus require changes in  images.tex  so as to work
with colored contents; e.g. I can program it so that the cropping bars are
always black, no matter what color are the contents and background-color. 

(Then there is the added complication in case the \pagecolor is black,
e.g. with white text --- sounds like a new Perl variable is needed to cope
with this case.)

> Best regards,
> Norbert

Thanks for the report Norbert.
By the way, have you been able to get  pnmcrop  to give a usage message ?
It seems that  pnmcrop --help  is no longer supported.
Is there an alternative ?

All the best,

	Ross Moore